The severe combined immune deficiency (SCID) will support local and metastatic growth of human tumor cells. Current evidence indicates the SCID mouse is more permissive of human tumor growth and may have greater clinical relevance than the nude mouse. Our results show human solid tumors (cell lines and fresh biopsy material), human acute myeloid leukemia cells and human lymphomas will grow in the SCID mouse. In addition, we confirmed and extended previous reports that human lymphoid cells will proliferate and function in the SCID mouse and in some cases undergo in vivo transformation to lymphoid malignancy. Growth of fresh human lymphoma specimens may be enhanced by using natural killer (NK) cell deficient SCID variants. The goal of this Program Project is to develop a better understanding of human cancer growth and metastasis and identify new treatment including novel drugs, chemosensitizers, peptides or biological agents alone or in combination. All new Mouse Core will assist Program Project Investigators with design of preclinical drug treatment experiments and investigations using the SCID mouse to study metastatic behavior. To ensure these experiments and evaluate the endpoints. Endpoints for drug effect include measurements of subcutaneous (SC) tumor size versus time, survival of treated versus control groups, gross and microscopic pathologic examination of SCID mouse tissues, fluorescence activated cell sorting (FACS) and immunohistochemical studies to detect human tumor markers, limiting dilution analysis and human Alu sequence hybridization analysis. The SCID Core will ensure that adequate numbers of mice are available for required experiments. The SCID mouse colony at the University of Arizona was established December 1988 and can produce up to 100 mice per week.